1. Field of the Invention
The present invention relates generally to laminated panels and, more particularly, to a laminated panel having a stainless steel foil core, wherein the core of the panel is a perforated core prepared by laminating and bonding together plural multi-layered sheets of stainless steel. The invention also relates to a process for producing the laminated panels.
2. Description of the Prior Art
Laminated panels such as honeycomb panels and the like have conventionally been used as structural materials in ceiling, wall and floor constructions as well as in ships and aircraft.
Known honeycomb panels have commonly been prepared by using an aluminum foil, a resin-impregnated paper, a cellulose ester sheet or some other type of plastic sheet as the honeycomb core material. Aluminum honeycomb panels are largely in use because of their light weight and high productivity.
However, laminated panels using aluminum cores of certain grades are readily corroded when contacted with aqueous systems, particularly saline water. With progress of the corrosion, their strength is remarkably decreased.
In contrast, laminated panels using paper and plastics are very light in weight and are not typically subject to the same types of corrosion as are aluminum cores, but they have a fault that they are readily deformed by heat and some of them are combustible.
If both corrosion resistance and heat resistance are taken into account, stainless steel is considered the best core material Nevertheless, no laminated panel made from stainless steel core has yet been developed which can be produced in an economically reasonable manner to make the use of stainless steel in such structures feasible.
Therefore, it would be desirable to provide a process for producing, with a certainty, a laminated panel which has a stainless steel core and which is excellent in strength, light in weight, abrasion resistant and heat resistant.
An example of a known cellular structure and a method of making the structure is disclosed in United Kingdom Patent Specification No. 850,197, wherein a honeycomb structure is formed by expanding a plurality of bands which have been coupled together by a plurality of smaller elements between the bands. According to the disclosure of the U.K. No. 850,197 patent, any material such as cardboard, paper, metal or synthetic resin may be employed in the construction of the cellular structure of the patent. However, the patent further discloses that where metal is used as the material, it is necessary to make the joints between the layers of material by effecting a spot welding or brazing. Such processes increase the cost of producing the cellular material and complicate the method.
Other examples of similar methods of constructing cellular material from layered sheets of folded material are disclosed in U.K. Patent Specification No. 1,151,097 and U.K. Patent Specification No. 1,214,291. The structures and methods disclosed in these patents are typical of the structures discussed above which employ paper, plastic or metal materials to form the sheets from which the cellular structures are produced. The U.K. Patent No. 1,151,097 discloses the use of seam welding or soldering as possible means for bonding metallic surfaces of the honeycombs.
It is known that stainless steel foil cannot be shaped in a honeycomb structure in the same manner as paper or aluminum since paper and aluminum possess little rigidity and reversion power while being easily deformable, whereas metal is more rigid and tends to revert to its previous shape more than does aluminum or paper.